Material cooler

ABSTRACT

A cooler for hot material such as cement clinker which includes a plurality of superimposed heat exchanger sections. Each of the sections includes an arrangement such as a series of alternately fixed and movable grates for moving material from the inlet of the section to the outlet of the section. A material breaker is positioned between the initial heat exchanger section and the second heat exchanger section. A material lock is provided between each section. The material is cooled by air flowing upwardly through the grate and material. Cooling air is introduced into a plenum chamber beneath the last section, flows upwardly through the material in that section and through the material in the succeeding sections and is eventually sent to the furnace as heated combustion air. Before passing through the initial section, water may be sprayed into the air to cool the same.

United States Patent Schreiner Aug. 29, 1972 [54] MATERIAL COOLER [72]Inventor: Paul Schreiner, 207 Gross-Han- Primary Examiner-Carroll Domysdorf, Germany Attorney-Jack L. Prather and Frank H. Thomson [73]Assignee: Fuller Company [57] ABSTRACT [22] Filed: May 1971 A cooler forhot material such as cement clinker Appl. No.: 146,368

which includes a plurality of superimposed heat exchanger sections. Eachof the sections includes an arrangement such as a series of alternatelyfixed and movable grates for moving material from the inlet of thesection to the outlet of the section. A material breaker is positionedbetween the initial heat exchanger section and the second heat exchangersection. A material lock is provided between each section. The materialis cooled by air flowing upwardly through the grate and material.Cooling air is introduced into a plenum chamber beneath the lastsection, flows upwardly through the material in that section and throughthe material in the succeeding sections and is eventually sent to thefurnace as heated combustion air. Before passing through the initialsection, water may be sprayed into the air to cool the same.

5 Claims, 1 Drawing Figure adv PATENTEmusze I972 3.686; 773

IINVENTOR PAUL saws/-51? TORNEY BACKGROUND OF THE INVENTION Thisinvention relates to a cooler for hot or burning material with a largenumber of cooling grates divided into a plurality of grate sectionsthrough which the material passes one after the other, whereby thecooling air of the first grate section can be conducted into the burningfurnace as combustion air. The invention is particularly suited tocooling cement clinker discharged from a rotary kiln.

In coolers of the kind to which the present invention relates, only thecooling air of the first grate section is supplied to the furnace assecondary air, or the cooling air first flows through the second coolersection in order to chill the hot material which is located there, andit then flows through the first cooler section from which it isconducted to the furnace. In the first case, the cooling air of thesecond grate section is blown off into the atmosphere, which results inheat losses and necessitates the use of dust collection apparatus beforebeing discharged to atmosphere. In the second case, the cooling airflows through the two grate sections in a direct current, i.e., throughthe hottest material first and then through the cooler material. Forheat management reasons it would be better to have an arrangement inwhich the cooling air flows through the succeeding sections in acountercurrent, i.e., through the cooler material first.

The accomplishment of this objective in existing coolers is essentiallyprevented by three factors. First of all, the cooling air must, from onesection to the next, run through a blower, if locks for the material areto be avoided; this requires an expensive intermediate removal of dustfrom the cooling air or it will lead to a considerable wear and tear onthe blower. Second, if the use of such blowers is to be avoided, thematerial must run through locks from one section to the next, which isimpossible not only because of the high temperature of the materialafter the first grate section but also because of the differing grainsize of the material. Third, the cooling air, which is conducted throughthe grates in a direction countercurrent to the flow of material,reaches the first grate section with an already comparatively hightemperature, so that it cannot achieve the cooling affects required forthe protection of the grate material used in the first stage.

SUMMARY It is the principal object of this invention to provide a novelcooler for hot material which overcomes the above mentioned problems.

It is a further object of this invention to provide a cooler for hotmaterial which recuperates at least some of the heat of the hot materialand substantially eliminates the necessity of venting cooling air toatmosphere and thereby substantially reduces heat losses and the use ofdust collectors which accompanies such venting.

The invention is intended, in spite of the conditions described, tocreate a cooler for burning material of the type mentioned in thebeginning, where the cooling medium can flow through the grate sectionscountercurrent to the flow of material.

The solution according to the invention consists in the combinationofthe features in that:

a. The known heat exchanger design is used, where several gratesections, following each other in the direction of movement ofthe'burning material, have the same cooling air current flow throughthem in reverse sequence and where locks for the material are arrangedbetween successive grate sections;

b. That a material breaker is arranged between the first and secondgrate sections, looking in the direction of movement of the material;

0. That devices are provided for the introduction of water into thecooling air current before the latter flows through the first gratesection.

These features supplement each other in such a manner that one feature,each, is made possible only through the presence of the other features.Thus it is necessary for the use of locks between the individual gratesections to make sure that the material is broken in connection with thefirst grate section. The arrangement of these locks makes it possible toconduct the cooling air current through all grate stages withoutintermediate blowers. We can prevent the overheating of the first gratesection, due to insufficient cooling of the air heated up in the othergrate sections, by introducing water before the first grate section. Dueto this water introduction, as a result of which the air temperature isreduced, we can attain such a low material temperature at the end of thefirst stage that a material breaker can be inserted at this place. Inthis way we can close the circle of mutually conditioning features. Thecooler design according to the invention is facilitated by the fact thata very specificplace in the cooler has been selected for thisintroduction of water.

The presence of the locks between the successive grate sections makes itpossible in each case to connect the under-chamber of a grate section,preceding in the direction of material movement, directly with the upperchamber of the following grate section. A particularly advantageous andcompact design for the cooler emerges whenever more than two gratesections are arranged in a zig-zag fashion above each other.

The devices for the introduction of the water are best made in the formof spray nozzles positioned in the upper chamber of the second gratesection.

The cooling in the first grate section and especially the adequatecooling of the grate in the highly-stressed first part of this gratesection, as well as the chilling of the material dropped from thefurnace can be achieved if a first part of the first grate section ishit with cold cooling air.

BRIEF DESCRIPTION OF THE DRAWING The invention is described inconnection with the annexed drawing wherein the single FIGURE is aschematic longitudinal.cross-section of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Three heat exchanger or gratesections 1, 2 and 3, which best belong to a design with alternatinglystationary and moving air permeable grate plates and of which theuppermost and first grate section is best designed in an inclinedfashion such as the heat exchanger shown in US. Pat. No. 2,431,799 arearranged above each other in a zig-zag fashion. The cooler sections 2and 3 are preferably horizontal coolers such as those shown in U.S. Pat.Nos. 2,846,778; 3,197,887; or 3,358,385. The beginning of the firstgrate sections 1 lies under the shaft 4 into which opens the dischargeend 5 of a furnace such as a rotary kiln. A breaker 6 of any suitabledesign that can be operated at the temperatures prevailing there ispositioned at the end of the first grate section.

The material dropped by the breaker is moved into a material lock shaft7 which is made between the outside wall 8 and a separating wall 9. Theseparating wall 9 has a slide member 10 positioned at its lower endwhich can be adjusted for regulatory purposes during operation of theapparatus or can be fixed. Two level measurement members 11 arepositioned in the lock shaft 7 of which the lower one is place so highthat the lock effect is still guaranteed when the filling level is justslightly below this member.

The lock shaft 7 opens at the beginning of grate section 2. A materiallock shaft 12 is positioned at the discharge end of section 2 and islikewise equipped with level measurement members 13 similar to members11. The partition 14 which forms part of the shaft 12 is equipped with aslide element 15 which corresponds to the element 10 in terms ofarrangement and operation.

The shaft 12 empties above the beginning of grate section 3 whichterminates in a third lock shaft 16 which is also equipped with levelmeasurement members 17 which control discharge members indicated in thedrawing as double butterfly valves 18 so that the lock shaft 16 willconstantly be so filled that the lock effect will be guaranteed. If theforce-controlled discharge members themselves have enough of a lockeffect, the plug-effect of the material which accumulates in shaft 16can be reduced or eliminated.

Cooling air is supplied to the lower chamber of grate 3 by means of ablower 19. This lower chamber is limited on the underside by funnels 20which catch the material falling through the grate and these funnels arelikewise provided with discharge locks which are indicated in theexample as double butterfly valves 21 which, in turn, can be controlledby level measurement members 22. If desired, the lower chamber can bedivided into compartments by suitable partitions with a separate blowersupplying cooling air to each compartment.

The level measurement members, which in each case are arranged in pairs,work in such a manner that the material is discharged as soon as theupper level measurement member has been reached, while the dischargeoperation is stopped as soon as the filling level drops to the lowerlevel measurement member.

The level measurement members 11 and 13 in look shafts 7 and 12 serve toregulate the material level in such a manner that there will always beenough filling material in these layers. They can act either upon theslide members 10 and 15, respectively, and/or upon the drive of thegrate sections 2, respectively 3, for the purpose of adjusting theirspeed and thereby adjusting the rate at which material is moved throughthe heat exchanger sections. The lock shafts insure that cooling airflows through the grates and material supported thereon and is notshort-circuited around the material.

The cooler housing, which encloses the three grate sections, iscompletely closed with the exception of shaft 4. The pressure of thecooling air, conveyed by blower 19, drops in three stages while passingthrough grate sections 3, 2, and 1, until it has reached in the upperchamber of grate section 1 the pressure at the furnace outlet which isnear atmospheric pressure.

By means of partition 23 in the lower chamber of the first grate section1, the first pan of the first grate section is protected against beinghit by the general cooling air current. This grate section, in themeantime, is connected to a separate blower 24 which supplied this gratesection with cooling air so that this highlystressed part of the firstgrate section will be effectively cooled and so that the materiaLdropped by the furnace into this area, will experience a rapidtemperature reduction. This feature will reduce the tendency of theinitial grates of the section 1 to fail before the other grates of thatsection due to exposure to extremely high temperature materialdischarged from the furnace.

Water spray nozzles 25 run into the lower chamber of the first gratesection. The injected water gives the cooling air current the moisturecontent desired for the secondary air and furthermore so reduces thetemperature of the cooling air current that sufficient cooling isachieved in the first grate section. The spraying of water can beregulated as a function of the secondary air temperature and/or theclinker terminal temperature. Both temperatures are reduced as a resultof the injection of water.

I claim:

1. A cooler for hot material including a plurality of heat exchangersections through which material to be cooled sequentially passes wherebycooling air which is heated by the hot material can be returned to afurnace as combustion air, the improvement comprising:

a plurality of flow connected heat exchangers each including means forsupporting the material to be cooled and advancing said material throughthe heat exchanger;

means for supplying cooling air for sequential passage through thematerial in each heat exchanger whereby cooling air passes through thecoolest material first and the hottest material last;

material lock means between each heat exchanger;

breaker means positioned between at least two heat exchangers; and

means for introducing water into the cooling air before it passesthrough the hottest material.

2. A cooler according to claim 1 wherein said heat exchangers aresuperimposed upon each other and each includes a lower chamber and anupper chamber separated by said means for supporting the material andthe lower chamber of one heat exchanger is directly connected with theupper chamber of the following section.

3. The cooler according to claim 2 wherein there are at least three heatexchangers arranged above each other so that material flows through thecooler in a zigzag pattern.

4. The cooler according to claim 1 wherein said means for introducingwater includes means for spraying water into the cooling air just priorto the cooling air passing through the heat exchanger containing thehottest material.

5. The cooler according to claim 1 further comprising means forsupplying additional cooling air directly to the heat exchanger whichreceives the hot material to be cooled at the point nearest the pointhot material flows into the cooler from a furnace. 5

1. A cooler for hot material including a plurality of heat exchangersections through which material to be cooled sequentially passes wherebycooling air which is heated by the hot material can be returned to afurnace as combustion air, the improvement comprising: a plurality offlow connected heat exchangers each including means for supporting thematerial to be cooled and advancing said material through the heatexchanger; means for supplying cooling air for sequential passagethrough the material in each heat exchanger whereby cooling air passesthrough the coolest material first and the hottest material last;material lock means between each heat exchanger; breaker meanspositioned between at least two heat exchangers; and means forintroducing water into the cooling air before it passes through thehottest material.
 2. A cooler according to claim 1 wherein said heatexchangers are superimposed upon each other and each includes a lowerchamber and an upper chamber separated by said means for supporting thematerial and the lower chamber of one heat exchanger is directlyconnected with the upper chamber of the following section.
 3. The cooleraccording to claim 2 wherein there are at least three heat exchangersarranged above each other so that material flows through the cooler in azig-zag pattern.
 4. The cooler according to claim 1 wherein said meansfor introducing water includes means for spraying water into the coolingair just prior to the cooling air passing through the heat exchangercontaining the hottest material.
 5. The cooler according to claim 1further comprising means for supplying additional cooling air directlyto the heat exchanger which receives the hot material to be cooled atthe point nearest the point hot material flows into the cooler from afurnace.